The Linux community is splitting over Microsoft's controversial claims that the open source operating system (OS) infringes on patents it holds.

Last week, Paris-based Mandriva became the third Linux vendor within five days to say it isn't interested in signing a licensing deal with Microsoft to avoid possible infringement claims. A blog posting to that effect by Mandriva chief exceutive Francois Bancilhon followed similar declarations by officials at Red Hat and Canonical, which oversees Ubuntu Linux.

But earlier this month, Microsoft announced collaboration agreements with Xandros and Linspire that included patent covenants absolving them of any charges that their Linux distributions infringe on Microsoft intellectual property. Those deals were similar to the highly publicised agreement that Microsoft and Novell, the developer of SUSE Linux, signed last autumn.

The intellectual property issue came to a head after Microsoft executives asserted last month that Linux and other open source technologies infringe on 235 of its patents. The Microsoft officials said that they wanted to sign more deals like the one with Novell, which agreed to pay Microsoft a share of the revenue from sales of SUSE Linux.

Kevin Carmony, chief executive of US-based Linspire, said in a statement issued 13 June that his company's agreement with Microsoft was designed to give users "improved interoperability, enhanced functionality and confidence".

But Mandriva's Bancilhon contended that "absolutely no hard evidence" has been produced showing that Linux or other technologies infringe on any patents. "We don't believe it is necessary for us to get protection from Microsoft to do our job, or to pay protection money to anyone," he wrote.

On 16 June, Ubuntu Linux founder Mark Shuttleworth wrote in his personal blog that Ubuntu and Canonical officials had declined to discuss any deals with Microsoft "under the threat of unspecified patent infringements". That came one day after Linux market leader Red Hat reiterated that it wasn't interested in negotiating an agreement.

In a statement emailed this week by Microsoft's public relations agency, David Kaefer, the software vendor's general manager of intellectual property and licensing, said Microsoft "remains committed to working with all companies that have a shared interest in building the bridge between open source and proprietary software."

"Microsoft has been buying up deals with little fish and companies that aren't quite making it financially," open-source advocate Bruce Perens said, referring to its agreements with Novell, Linspire and Xandros. But the vendors that have resisted its offers are taking the right stand, he said.

Jonathan Eunice, an analyst at Illuminata agreed that companies like Xandros and Linspire were "softer targets" for Microsoft. Vendors like Red Hat and Canonical "don't need to take out the insurance policies" with Microsoft on its infringement claims, Eunice said.

But Laura DiDio, an analyst at Yankee Group Research said it makes sense for some of the Linux vendors to sign deals with Microsoft that indemnify their customers against any claims.

"It can impact enterprise users if somebody decides to sue for patent infringement ... and they don't have any protection in place," DiDio said. "That is always a danger."